JP4230195B2 - Multi-resolution photodiode sensor array for optical encoders - Google Patents

Abstract

A method of controlling the resolution of an optical encoder for providing position information of an object which moves along a certain measuring direction where the optical encoder includes a light source that emits light and a data track that moves relative to the light source. The method includes directing modulated light from the data track to a plurality of photodiodes of a detection system having a resolution that has a first value and changing the resolution of the detection system to a second value without altering an arrangement of the plurality of photodiodes of the detection system during the changing from the first value to the second value. <IMAGE>

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photodiode sensor used for various optical resolutions. In particular, the present invention relates to photosensor arrays for optical encoders used for various resolutions.
[0002]
[Prior art]
Optical encoders that measure the relative position between two movable objects are well known. Just as it is possible to measure the relative position along the direction of rotational movement, it is possible to measure the relative position along the direction of linear movement. In this system, one object is often connected to a scanning scale while the other object is connected to a scanning unit. In the case of a linear encoder, a linear scale with a linear scale is used, while in the case of a rotary encoder, a code disk with a circular scale is used. A scanning unit used for linear or rotational movement has one or more light sources and one or more photoelectric sensing elements. For example, a photodiode is often used as a detection element.
[0003]
In recent years, linear encoders and rotary encoders in which a large number of photodiodes as detection elements are combined with each other have become increasingly popular. Such a detection arrangement is sometimes called a phased array. Such an encoder and detector are described in US Pat. No. 6,175,109. The entire contents of this are described herein by reference.
[0004]
In the above-described detector arrangement embodiment, a plurality of photodiodes are arranged in an array on a semiconductor chip. The arrangement of these photodiodes must be ordered / designed for each encoder configuration in a unique manner. This means that the geometrical arrangement required for the photodiodes, such as the width and spacing of the photodiodes, depends on the scanning arrangement, in particular the scale period of the scanning scale being scanned. There is a well-defined arrangement of photodiodes for a certain measurement resolution. Therefore, if it is necessary to change the scanning arrangement or the resolution of the encoder, it is necessary to change the arrangement of the photodiodes to a desired scanning arrangement or resolution. In this case, a great deal of design work is required to change the layout of the photodiode array.
[0005]
To solve this problem, EP 0 710 819 describes the use of a single photodiode assembly having a plurality of photodiodes for several different scan scales that exhibit different scale periods. put forward. For this purpose, only a certain number of photodiodes out of the available photodiodes have to be activated in response to the scanning scale. An adaptation process is necessary to determine each one of the photodiodes that must be activated for a particular scan scale. The point that a complex ASIC is required to control this adaptation process is a major drawback of this system. Another drawback is that the system's adaptation phase requires special tooling discs. In addition, a circuit associated with a large memory space is required on the carrier substrate. This carrier substrate goes against the possible miniaturization of the system.
[0006]
Another disadvantage of the system described in EP 0 710 819 is the index sensor of the system for measuring absolute position. In particular, disks having a pattern of openings that match the pattern of index sensors allow light to pass through these index sensors. This light illuminates the index sensor at only one point per revolution. The signal when part of the index sensor is illuminated is significantly smaller than when the entire index sensor is illuminated simultaneously.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to easily change the resolution of a detector array while allowing the detector array to have a desired small size.
[0008]
Another object of the present invention is to change the resolution of the detector array without using matched phase.
[0009]
Another object of the present invention is to improve the strength of the absolute and relative position signals generated by the detector array at multiple resolutions.
[0010]
A first aspect of the present invention relates to an optical encoder that provides position information of an object moving along a specific measurement direction. The encoder has a light source that emits light and a data track attached to an object that moves relative to the light source. This data track has a plurality of variable regions that receive light and exhibit different optical properties of a particular resolution. A detection system receives the modulated light from the data track and generates a position signal from the received light. The detection system has a photodiode array that receives the modulated light from the data track, and a resolution selection unit connected to the photodiode array. This resolution selection unit controls the resolution of the photodiode array. In this case, all photodiodes associated with the photodiode array are activated regardless of the resolution selected by the resolution selection unit.
[0011]
The second aspect of the present invention relates to a method for controlling the resolution of an optical encoder that provides position information of an object moving along a certain measurement direction. In this case, the optical encoder has a light source that emits light and a data track that moves relative to the light source.
[0012]
A third aspect of the present invention relates to an optical encoder that provides position information of an object. The optical encoder has a light source that emits light and a data track mounted on an object that moves relative to the light source. The data track has alternating regions of different optical properties that receive light and have a specific resolution. The detection device receives light from the data track and generates an index signal from the received light. The detection system has an index photodiode array that receives light from the data track and generates an index signal, and a resolution selection unit connected to the index photodiode array. This resolution selection unit controls the index signal.
[0013]
The fourth aspect of the present invention relates to a method for controlling an index signal of an optical encoder that provides position information of an object moving along a predetermined measurement direction. In this case, the optical encoder has a light source that emits light and a data track that moves relative to the light source and exhibits a given resolution. The method detects light from a data track to a plurality of photodiodes of the index photodiode array without changing the placement of the photodiodes of the index photodiode array, and includes detecting one or more of the index photodiode arrays. The index signal is generated by changing the active state of the photodiode.
[0014]
Each aspect of the present invention allows the detector array to be appropriately sized, while easily changing the resolution of the detector array.
[0015]
Each aspect of the present invention provides the advantage of not requiring a matching phase to determine the photodiodes to be activated in the array for a particular resolution. The elimination of the start phase further provides the advantage that no special tooling disk is required as is necessary for the system described in EP 0 710 819.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, these items and other features and advantages of the present invention will be described in detail with reference to the drawings.
[0017]
FIG. 1 schematically shows a cross section of an optical encoder according to a preferred embodiment of the present invention. In particular, the illustrated optical encoder is a rotary encoder 100 that generates position information relating to the motion of two rotating objects. The rotary encoder 100 can be used in applications involving, for example, a brushless motor.
[0018]
The optical encoder 100 includes a code gear 102 having a single data track 104 as shown in FIGS. 1-3, 5, 6, 8, 9, 11. The code gear 102 is installed on a shaft (not shown) that rotates about an axis, and moves / rotates along the measurement direction. The rotating shaft may be a rotor of a brushless DC motor. Furthermore, the optical encoder 100 includes a scanning unit 106 that scans the data track 104 photoelectrically. As shown in FIG. 1, the scanning unit 106 includes a light source 110 and a lens 112, preferably a condenser lens or a focusing lens. Since the details of the mechanical structure are well known to those skilled in the art, the structure of the encoder 100 is only shown schematically.
[0019]
As shown in FIGS. 1 and 2, the light 114 emitted by the light source 110 is transmitted through the data track 104 of the code gear 102 that is collimated by the condenser lens 112 and rotates with respect to the light source 110. Light 116 modulated by the rotating data track 104 is received by the photodetector array 118 of the detection system 120. The detected signal is processed in an evaluation unit not shown in FIGS.
[0020]
As shown in FIGS. 1-3, 5, 6, 8, 9, and 11, the data track 104 alternates with different optical properties, such as alternating transparent bars 122 and opaque bars 124. Has an incremental pattern of regions. If the optical encoder 100 is configured to use an incident light data track, the data track can be configured with regions where alternating high and low reflectivity. Further, the photodetector array 118 is composed of one incremental photodiode array 126 and two index photodiode arrays 128 and 130. The photodiode arrays 126, 128, and 130 have a plurality of photodiodes 132, 134, and 136, respectively. These photodiodes 132, 134, and 136 are arranged in a separate array on the opto-ASIC semiconductor chip 138. The opto-ASIC semiconductor chip 138 is mounted on the PC board 139.
[0021]
As shown in FIG. 3-11, the incremental photodiode array 126 has 96 photodiodes 132. In this case, adjacent photodiodes are arranged equiangularly. These photodiodes as a group then define a range of angles of about 9.2 °, for example 9.22 °. As a result, the individual photodiodes have a pitch corresponding to the desired maximum resolution, such as 1012. The linear spacing between adjacent photodiodes 132 is constant. The minimum spacing between adjacent photodiodes 132 is approximately 5 μm due to the molding process design rules that limit the maximum width of the photodiodes. Each of the four photodiode sets or groups is arranged within one grating period of the code disk pattern. Adjacent photodiodes in each set are arranged relative to each other. This results in a 90 ° phase lag between the output signals of adjacent photodiodes. Thus, four adjacent photodiodes have relative phases of 0 °, 90 °, 180 °, and 270 °. In FIG. 3, 5, 6, 8, 9, and 11, these signals having different phases are represented by A! , B, A, B! It is written.
[0022]
Incremental photodiode array 126 has 16 conductors 140. These leads 140 are internally connected to a photodiode 132 and a lead 142 extending from three incremental data resolution selection units 144, 146, 148. As shown in FIGS. 3, 4, 6, 7, 9, 10, each incremental data resolution selection unit 144, 146, 148 has 16 conductors 150. These conductive wires 150 are connected to a group of 16 conductive wires 140 and are connected to four output signal lines 152.
[0023]
Each incremental data resolution selection unit 144, 146, 148 has a switching signal line 154, 156, 158, respectively. The switching signal lines 154, 156, and 158 are selectively connected through 16 semiconductor switches 160 to the conductor 150 associated with the incremental data resolution selection unit corresponding to these switching signal lines. Each of the semiconductor switches 160 is always in a conductive state or a non-conductive state. The semiconductor switch 160 is used to connect the 16 conductors 140 to the four output signal lines 152 in different combinations. Each of the output signal lines 152 has incremental scanning signals A, B, A! , B! Is output. While these above-described switches are semiconductor switches, other switches are possible, such as switches including metal links.
[0024]
As shown in FIGS. 3, 5, 6, 8, 9, 11, and 12 A, the index photodiode array 128 and the photodiode 134 associated with the index photodiode array 128 generate the first index signal Z. To do. The index photodiode array 130 and the 14 photodiodes 136 of the index photodiode array 130 are connected to the second index signal Z! Is generated. Individual photodiodes in the index photodiode array 128, 130 are enabled by the same signal. This same signal allows the individual photodiodes 130 of the photodiode array 126. These individual photodiodes 130 are activated to achieve the desired encoder resolution.
[0025]
When the encoder is fully rotated, the index signals Z and Z! Outputs a special pattern. In particular, the index signals Z, Z! Are electrically compared and processed to output one output pulse for each revolution of the encoder 100. The encoder 100 absolutely locates all other signals of the encoder.
[0026]
So, index signals Z, Z! Is completely differential. Z! Every portion of the signal code disc pattern has an opaque region. On the other hand, the code disk pattern for the Z signal has an opening. Such differential characteristics eliminate common mode noise. Index signals Z, Z! Is used to determine absolute information. This unique pattern is generated by a special optical pattern. This special optical pattern is optimized to achieve a pulse with maximum contrast between a single optical cycle and the “background” signal that is always present. This definition depends on this optical cycle. In order to provide flexibility in selecting the resolution to be detected according to the present invention, it is necessary to change the index signal based on the resolution to be selected. As a result, various optimized patterns can be used for each resolution. Thus, depending on whether the particular pattern to be detected requires an output signal, signals from the detectors of arrays 128, 136 are sent to this output signal.
[0027]
Fourteen photodiodes 136 of the index photodiode array 128 are arranged. As a result, when these photodiodes 136 are fully illuminated through corresponding openings or bars 122 in the data track 104, a single large index pulse is generated or formed. Similarly, the photodiodes 134 of the index photodiode array 130 are arranged. As a result, when these photodiodes 134 are fully illuminated through corresponding openings or bars 122 in the data track 104, a single large index pulse is generated or formed. The light received by the index photodiode arrays 128, 130 is not modulated. The angular widths of the index photodiode arrays 128, 130 are selected so that a good contrast between the index signals is achieved for a range of resolution. Each of the photodiodes 134 and 136 has a width of about 68 μm. Non-conductive material is present between adjacent photodiodes 134 and photodiodes 136. As a result, these adjacent photodiodes are about 5.8 μm apart. Each of the index photodiode arrays 128, 130 is arranged at a pitch that coincides with one data region (360 ° e) of the highest resolution desired, such as 1012. The photodiodes 134 and 136 have a radial pitch equal to four times the pitch of the photodiode 132. Due to the various scanning structures on the code disc, various index signal waveforms Z, Z! Occurs. Because a code disk with multiple different resolutions can be used, 14 photodiodes 134 and 14 photodiodes 136 are selectively activated to provide the sharpest index pulse for the unique code disk 102. Is realized. However, the general principle of generating these signals is common to both index signal photodiode arrays 128,130.
[0028]
In the angle optical encoder as shown in FIGS. 1-13A-B, the photodiode arrays 126, 128, and 130 need to have one common axis. The angular relationship between these photodiode arrays 126, 128, and 130 need not be a special value, but must be a constant and known value.
[0029]
The necessary relationship between the index photodiode array 128, 130 and the incremental photodiode array is such that the radial pitch of the individual index array elements 134, 136 is four times the pitch of the incremental array elements 132. Or the width of one data cycle. Since the index array pattern for all possible encoder resolutions must be made from the same array of index detector elements 134, 136, each resolution is different to obtain the largest single signal from the available detector elements. Request a combination.
[0030]
As shown schematically in FIG. 13A, the signals A, A! From the incremental photodiode array 126! , B, B! Is amplified by the impedance conversion amplifier 200. And complementary signals A, A! And B, B! Are compared with each other via the comparator 201. Similarly, the signals Z, Z! Generated by the index photodiode arrays 128, 130! Are amplified by the impedance conversion amplifier 202 and compared by the comparator 203. Then, signals from the comparators 201 and 203 are input to the data processing element 204. In order to output to the detected frequencies 1X, 2X, 4X, and 8X, the data processing element 204 includes all 16 output signals 206 appropriately phase-synchronized from the 16 phase-synchronized analog voltage signals. Is output. The output signal 206 is output to the digital logic unit 214. This digital logic 214 is programmed from these output signals 206 and the interpolator 216 to generate a high frequency signal by combining four basic signals that are 90 ° apart from each other (regardless of the selected resolution). Combine interpolation choices. As shown in FIG. 13A, several output signals are generated from chip 138. For example, two data pulses 218, 220 with a digital 50% duty cycle are output 90 ° apart. Furthermore, the signal AB or A! B! A single digital index pulse is generated. For testing and evaluation purposes, three programming such as digital output, analog test mode 1 and analog test mode 2 are possible at output terminals 230, 232 and 234 as indicated by the labels for outputs separated by / It is.
[0031]
Selection of the resolution of the arrays 126, 128, 130 is performed through the serial test and programming interfaces 212, 138, as are many other selectable options in electron optics.
[0032]
The single-ended communication unit 224 shown in FIG. 13B is the same for all resolutions. The communication unit 224 generates three signals whose phases are electrically shifted by 120 °. These three signals are generally referenced to the rising edge of the index signal and are used to align the motor (brush axis) on which the encoder is mounted. A method for obtaining a pseudo-common mode reference signal between three single-ended communication signals is described in US Pat. Nos. 5,936,236 and 6,175,109. All these contents are mentioned here by reference. The above-described method for generating a common mode reference signal can be implemented using CMOS technology.
[0033]
Based on the above description of the photodiode arrays 126, 128, and 130, the ability to change the resolution while using the same photodiode arrays 126, 128, and 130 will be described below. Particularly preferably, there is always a certain number and arrangement of index and signal photodiodes 134,136. In the above description and the resolution of N means below, the complete circumference of the scanned data track 104 has a total of N alternating transparent bars 122 and opaque bars 124.
[0034]
In order to achieve 1012 resolution when the data track has 1012 resolution, the incremental data resolution selection unit 144 is activated via the activation signal generated by the resolution selection logic of the ASIC semiconductor chip 138, and the switching signal Transmit along line 154. Upon receipt of the activation signal, the incremental data decomposition selection unit 144 opens and closes the semiconductor switch 160 of the unit 144. As a result, a specific combination of 16 conductors 140 is connected to the four output signal lines 152. If a resolution of 1012 is to be achieved, the incremental data resolution selection unit 144 groups the photodiodes 132. As a result, four adjacent photodiodes are formed in one group. As shown in FIGS. 3 and 4, each group of four photodiodes is connected to the output signal line 152. As a result, the signal from the first photodiode in the group is A! The signal from the second photodiode in this group is sent to the output signal line 152, and the signal from the third photodiode in this group is sent to the An output signal line 152. The signal from the fourth photodiode in this group is B! It is sent to the output signal line 152. As shown in FIGS. 3 and 4, as a result of such a connection, multiple photodiodes 132 are interdigitated with each fourth photodiode 132 acting as a group of photodiodes, resulting in a single output. Connected to the signal line 152.
[0035]
Further, the index resolution selection unit 153 selects a specific photodiode among the photodiodes of the index photodiode arrays 128 and 130 for a specific resolution. In this case, all photodiodes are activated when selected. Such a selection is performed via the switching signal line 154 and the switch 160 '. The activated photodiodes 1, 14, and 15 are always connected to the switching signal lines 154, 156, and 158 for all resolutions. For the remaining active photodiodes, photodiodes 2 and 12 have two separate lines connected to switching signal lines 156 and 158 and a switch 160 '. Photodiodes 3, 8, and 10 have separate lines connected to switching signal lines 154 and 158 and a switch 160 '. The photodiode 4 is connected to the switching signal line 154 via the switch 160. The photodiodes 5, 6, and 11 are connected to the switching signal line 156 via the switch 160 ′. The photodiode 9 is connected to the switching signal line 158 via the switch 160 ′. When a resolution of 1012 is desired, the index selection unit 153 activates a specific switch 160 ′ via the switching signal line 154. As a result, as shown in FIGS. Only 1,3,4,9,10,13,14 are selected. Switching signal line 154 and switch 160 'are programmed for a specific resolution via an external code feed through a serial interface. The resolution of the photodiode arrays 128, 130 is simultaneously selected by the same encoded programming signal that selects the resolution of the incremental photodiode array 126.
[0036]
The photodiodes activated via the resolution selection unit 153 in the index photodiode array for a particular resolution are determined by determining the combination of photodiodes that optimizes the index signal for the particular resolution. In other words, the photodiode is selected to give the largest ratio of the large center signal to the smallest signal immediately adjacent for a particular resolution. As a matching disc pattern passes over the photodiodes, a computer program can be prepared to compare the combinations of these photodiodes and select the optimal ratio combination.
[0037]
When the resolution is 1012, the 1012 count disk passes over 14 photodiodes as shown in FIG. After testing all possible combinations, no. When seven photodiodes 1, 3, 4, 8, 10, 13, and 14 are activated, an optimum ratio is determined. This combination becomes the center signal from the seven photodiodes when the disk pattern and the sensor pattern overlap. As the disk approaches and moves away from the center position, the maximum of the two diodes and the disk pattern coincide. The result is a signal to non-signal ratio of 7: 2. This difference allows the electronics to process only the center signal with the desired width of a single data cycle, rather than the strength of 7 diodes.
[0038]
For a resolution of 506, the data cycle is twice the width of 1024 individual photodiodes. To compensate for the length of this data cycle, adjacent photodiodes of 14 individual photodiodes are grouped in pairs. Each pair of photodiodes grouped is treated as a single photodiode for 506 resolution. Therefore, the optimal index signal must be determined for such a pair / group of seven photodiodes. The optimal signal to non-signal ratio is a choice of 506 resolution configurations for the four groups of photodiodes 1 & 2, 5 & 6, 11 & 12, 13 & 14. The result is a signal to non-signal ratio of 4: 1.
[0039]
For a resolution of 253, the data cycle is four times the width of 1024 individual photodiodes. However, an array of 14 individual photodiodes is only 3.5 253 resolution cycle width. Since it is impossible to group adjacent detectors to 3.5, a compromise is made by grouping adjacent detectors. As a result, a 253 resolution detector is three 253 resolution cycle widths apart while being separated by a 253 resolution pitch. As a result, four groups of four virtual photodiodes are formed. In this case, the width of each virtual photodiode is equal to 3/4 of the actual photodiode width. When three of the four groups are selected, the optimal index signal is found based on the configuration described above. These three groups correspond to photodiodes 1, 2 &3;8; 9 &10; 12, 13 & 14. The result is a signal to non-signal ratio of 3: 1.
[0040]
The resolution can be changed from any one of the resolutions 1012, 506, 253 to any of the other resolutions. For example, other resolutions are possible for the incremental photodiode array 126 when other code gears 102 are used or when other resolutions are used for the code gears 102. Such a resolution can be realized simply by activating the semiconductor switch 160 of the corresponding incremental data resolution selection unit and selecting all of these switches to energize to select the required resolution. Therefore, the resolution can be changed without changing the arrangement of the photodiodes in the photodiode array 126. The semiconductor switch 160 is activated by resolution selection logic. This resolution selection logic is performed in the same opto-ASIC semiconductor chip 138 already described.
[0041]
An example of changing the resolution of the photodiode array 126 is shown in FIGS. 6-8. In this example, a resolution of 506 is activated by sending an activation signal along the resolution switching signal line 156. This switching signal line 156 causes the incremental data resolution selection unit 146 to open and close the semiconductor switch 160 of this unit 146. As a result, a specific combination of 16 conductors 140 is connected to the four output signal lines 152. In particular, an incremental data resolution selection unit 146 defines a group of photodiodes 132 in the photodiode array 126. As a result, each of the eight photodiodes adjacent to each other in succession is formed in one group. Thus, 12 groups of 8 photodiodes are formed. As shown in FIG. 7, each group of eight photodiodes is connected to the output signal line 152. As a result, the signal from the first two photodiodes in the group is A! The signal from the second photodiode pair in this group is sent to the output signal line 152, and the signal from the third photodiode pair in this group is sent to the B output signal line 152. And the signal from the fourth photodiode pair in this group is B! It is sent to the output signal line 152. In essence, when the photodiode is paired, the output signal A! , A, B! , B, the effective size of the detection area corresponding to the photodiodes generating B is increased by a factor of two. Thus, the resolution of the array is increased by a factor of two. In addition, as shown in FIGS. Only 1, 2, 5, 6, 11-14 are selected by the index resolution selection unit via the resolution switching signal line 156.
[0042]
In another example, a resolution of 253 is activated by sending an activation signal along the resolution switching signal line 158. This switching signal line 158 causes the incremental data resolution selection unit 148 to open and close the semiconductor switch 160 of this unit 148. As a result, a specific combination of 16 conductors 140 is connected to the four output signal lines 152. In particular, an incremental data resolution selection unit 148 defines a group of photodiodes 132 in the photodiode array 126. As a result, each of the 16 photodiodes adjacent to each other in succession is formed in one group. Accordingly, six groups of 16 photodiodes are formed. As shown in FIGS. 9 and 10, each group of 16 photodiodes is connected to the output signal line 152. As a result, the signal from the first four photodiodes in the group is A! The signal from the second four photodiodes in this group is sent to the output signal line 152, and the signal from the third four photodiodes in this group is sent to the B output signal line 152. The signal from the fourth four photodiodes in this group sent to line 152 is B! It is sent to the output signal line 152. Further, the photodiodes No. of the index photodiode arrays 128 and 130 are not limited. Only 1-3, 8-10 and 12-14 are selected by switching the switching signal line 158 and the switch 160 'via the index resolution selection unit 153.
[0043]
While the example described above demonstrates changing the resolution of the incremental photodiode array 126, the appropriate combination of available index photodiodes 134, 136 is selected that produces an index signal with the appropriate resolution. It is also possible.
[0044]
In the example described above, a low resolution of 506, 253 is generated by grouping the photodiodes 132 twice. Of course, other resolutions are possible using the same principle described above with respect to the example of FIGS. 1-13A-B by grouping the photodiodes 132 with the integer N. Here, N = 3, 4, 5,...
[0045]
The advantage of the above example is that four output signals A, A! , B, B! The total number of photodiodes connected to each of these is constant regardless of the resolution selected for the optical encoder 100. In addition, all photodiodes 132 are used for each resolution selected by the optical encoder 100. This is in contrast to the system in which the array elements described in EP 0 710 819 are activated based on the matching phase. In this adaptive phase, the photocell assembly is scanned and the output of the photocell assembly is evaluated. In the example already described, when a total of 96 photodiodes 132 are used, each of the four output signals has 24 photodiodes associated with it. Keeping the number of photodiodes per signal constant for any resolution improves post-processing of the signal.
[0046]
Further, in the optical encoder 100 described above, the resolution is switched during operation of the optical encoder 100 by using a control mechanism. It is also possible to switch the resolution as a single decision at any time during production. Regardless of the switching mode, in this example of the invention, the signal passing through the switch operates fast and the switch operation is slow.
[0047]
The form of the invention described is a preferred embodiment, and various changes in the shape, size and arrangement of the parts are allowed without departing from the concept of the invention or the claims. For example, the present invention is not limited to a rotary encoder. The present invention can also be applied to a linear encoder having data tracks arranged in a straight line. The present invention can be applied to other resolutions by grouping adjacent photodiodes in various groups, such as groups larger than four. Furthermore, the sensor array may be realized in the form of a semiconductor chip separated from the opto-ASIC chip. Furthermore, various optical principles can be realized based on the present invention, such as the arrangement of emitted light shown in FIG. 1 and the arrangement of reflected light shown in FIG.
[0048]
In another example schematically shown in FIGS. 14 and 15, the optical encoder of FIGS. 1-13 is modified such that a magnetic encoder 300 having the same principle as the encoder 100 already described is provided. 14-17, like numbers are used for elements similar to those shown in FIG. 1-13. The porcelain encoder 300 does not require a light source. In addition, the data track 304 of the rotatable code gear 302 installed on the shaft has alternating regions with different porcelain characteristics. Detector array 318, incremental detector array 326 and index and detector array 328, 330 are similar to detector arrays 132, 134, 136, respectively. In this case, the photodiodes 132, 134, and 136 are replaced with magnetic field detectors 332, 334, and 336, respectively. The signal generated by the detector array 326 is processed and the resolution of the porcelain encoder 300 is processed and controlled by the semiconductor chip 338. The circuit is similar to the circuit shown in FIGS. 13A-B.
[0049]
In the arrangement of the reflected light already described, the optical encoder of FIG. 1-13 is modified so that the optical encoder 400 having the same principle as the encoder 100 already described is provided. In FIG. 18, similar numbers are used for similar elements as shown in FIGS. 1-13. In the optical encoder 400, the light source 100 is installed with respect to the semiconductor chip 138 so that the scanning unit 106 ′ has the detector array 118. Further, the reflection lens 402 is installed so that the code gear 102 is positioned between the light source 110 and the reflection lens 402. Thus, the light from the light source 110 passing through the rotatable code gear 102 is reflected by the reflective lens 402 so that the light reaches the detector array 118, the incremental detector array 126 and the index and detector arrays 128, 130. The reflected light returns to the code gear 102. The signal generated by the detector array 126 is processed and the resolution of the optical encoder 400 is processed and controlled by the semiconductor chip 138. The circuit is similar to the circuit shown in FIGS. 13A-B.
[Brief description of the drawings]
FIG. 1 is a schematic side view of an embodiment of an encoder having a photodiode array of the present invention.
FIG. 2 is an enlarged view of an encoder having the photodiode array of FIG.
FIG. 3 schematically illustrates the encoder and photodiode array of FIG. 1 when configured to provide 1012 resolution and 1012 resolution disk patterns.
4 is a schematic enlarged view of a transmission gate of the encoder and photodiode array of FIG. 3;
5 is a schematic enlarged view of an index photodiode and an incremental photodiode of the encoder and photodiode array of FIG. 3;
FIG. 6 schematically illustrates the encoder and photodiode array of FIG. 1 when configured to provide a resolution of 506 and a resolution of 506 disk patterns.
7 is a schematic enlarged view of a transmission gate of the encoder and photodiode array of FIG. 6. FIG.
FIG. 8 is a schematic enlarged view of an index photodiode and an incremental photodiode of the encoder and photodiode array of FIG. 6;
FIG. 9 schematically illustrates the encoder and photodiode array of FIG. 1 when configured to provide 253 resolution and 253 resolution disk patterns.
10 is a schematic enlarged view of a transmission gate of the encoder and photodiode array of FIG.
FIG. 11 is a schematic enlarged view of the index photodiode of the encoder and photodiode of FIG. 10;
12A is a schematic top view of the index array of FIGS. 1-11. FIG.
FIG. 12B is a schematic top view of the activated photodiode of the index array of FIGS. 1-11 when configured to provide an index signal for each resolution disk pattern of 1012, 506, and 253;
(C) Schematic top view of the activated photodiode of the index array of FIGS. 1-11 when configured to provide an index signal for each resolution disk pattern of 1012, 506, and 253.
(D) Schematic top view of the activated photodiode of the index array of FIGS. 1-11 when configured to provide an index signal for each resolution disk pattern of 1012, 506, and 253.
13A schematically illustrates an example of processing electronics used in the encoders of FIGS. 1-12 and 14-17. FIG.
(B) schematically shows an embodiment of processing electronics used in the encoders of FIGS. 1-12 and 14-17.
FIG. 14 is a schematic side view of an embodiment of the magnetic encoder and detector array of the present invention.
FIG. 15 schematically illustrates the magnetic encoder and detector array of FIG. 14 when configured to provide 1012 resolution and 1012 resolution disk patterns.
FIG. 16 schematically illustrates the magnetic encoder and detector array of FIG. 14 when configured to provide a resolution of 506 and a resolution of 506 disc patterns.
17 schematically illustrates the magnetic encoder and detector array of FIG. 14 when configured to provide 253 resolution and 253 resolution disc patterns.
FIG. 18 is a schematic side view of a second embodiment of the optical encoder and detection array of the present invention.
[Explanation of symbols]
100 optical encoder
102 Code gear
104 Data track
106 Scanning unit
110 Light source
112 lenses
114 light
116 modulated light
118 Photodetector array
120 detection system
122 Transparent bar
124 Opaque Bar
126 Incremental photodiode array
128 index photodiode array
130 Index Photodiode Array
132 Photodiode
134 Photodiode
136 photodiode
138 Opto ASIC semiconductor chip
139 PC board
140 conductor
142 Conductor
144 Incremental data resolution selection unit
146 Incremental data resolution selection unit
148 Incremental data resolution selection unit
152 Output signal line
153 Index resolution selection unit
154 Switching signal line
156 Switching signal line
158 Switching signal line
160 Semiconductor switch
200 Impedance conversion amplifier
201 Comparator
202 Impedance conversion amplifier
203 comparator
204 Data processing element
206 Output signal
212 interface
214 Digital logic
216 Interpolator
218 Data pulse
220 data pulses
222 Index pulse
224 communication unit
230 Output terminal
232 output terminal
234 output terminal
300 Magnetic encoder
302 Code gear
304 data tracks
318 Detector array
326 Incremental detector array
328 Index detector array
330 Index detector array
332 Magnetic field detector
334 Magnetic field detector
336 Magnetic field detector
400 Optical encoder
402 reflective lens

Claims (16)

In an optical encoder that provides position information of an object moving along a specific measurement direction, the optical encoder:
A light source that emits light;
A data track mounted on an object that moves relative to this light source;
It consists of a detection system that receives the modulated light from this data track and generates a position signal from this received light,
This data track that receives light is composed of alternating regions of different optical properties of a specific resolution,
This detection system is:
A photodiode array for receiving the modulated light from the data track;
It consists of a resolution selection unit connected to the photodiode array, the resolution selection unit controls and selects the resolution of the photodiode array, in which case all photodiodes associated with the photodiode array are It starts regardless of the resolution selected by this resolution selection unit. The optical encoder according to claim 1, wherein the resolution selection unit controls the resolution by controlling an effective size of a detection region corresponding to the photodiode of the photodiode array that generates the output signal. The optical encoder according to claim 1, wherein the resolution selection unit defines a plurality of groups of photodiodes in the photodiode array. 4. The optical encoder according to claim 3, wherein the group of photodiodes is composed of a single photodiode. 4. The optical encoder according to claim 3, wherein the group of photodiodes is composed of at least two adjacent photodiodes. 4. The optical encoder according to claim 3, wherein the group of photodiodes is composed of at least four adjacent photodiodes. 4. One of the groups of photodiodes corresponds to the first phase of the first output signal, and the second group of these groups corresponds to the second phase of the second output signal. The optical encoder described. One of the groups of photodiodes corresponds to the first phase of the first output signal, the second group of these groups corresponds to the second phase of the second output signal, and the second of these groups. 5. The optical encoder according to claim 4, wherein the three groups correspond to the third phase of the third output signal, and the fourth group of these groups corresponds to the fourth phase of the fourth output signal. One of the groups of photodiodes corresponds to the first phase of the first output signal, the second group of these groups corresponds to the second phase of the second output signal, and the second of these groups. 5. The optical encoder according to claim 4, wherein the three groups correspond to the third phase of the third output signal, and the fourth group of these groups corresponds to the fourth phase of the fourth output signal. One of the groups of photodiodes corresponds to the first phase of the first output signal, the second group of these groups corresponds to the second phase of the second output signal, and the second of these groups. 6. The optical encoder according to claim 5, wherein the three groups correspond to the third phase of the third output signal, and the fourth group of these groups corresponds to the fourth phase of the fourth output signal. One of the groups of photodiodes corresponds to the first phase of the first output signal, the second group of these groups corresponds to the second phase of the second output signal, and the second of these groups. The optical encoder according to claim 6, wherein the three groups correspond to the third phase of the third output signal, and the fourth group of these groups corresponds to the fourth phase of the fourth output signal. The detection system further includes a switching signal line, and the switching signal line is connected to the resolution selection unit via a plurality of switches, and these switches output the output from the photodiode array to the plurality of output lines. The optical encoder according to claim 1, wherein each output line has a particular phase lag associated therewith. The optical encoder according to claim 1, wherein the resolution of the photodiode controlled by the resolution selection unit corresponds to a specific resolution of the data track. The detection system further comprises an index photodiode array that receives light from the data track and generates an index signal;
A resolution selection unit is connected to the index photodiode array, and the resolution selection unit controls the contrast of the index signal, in which case all photodiodes associated with the index photodiode array are 2. The optical encoder according to claim 1, which is activated regardless of the resolution selected by the resolution selection unit. The optical encoder of claim 14, further comprising a second photodiode array that receives light from the data track and generates a second index signal. 15. The optical encoder according to claim 14, wherein the resolution selection unit selectively activates a plurality of photodiodes in the index photodiode array to optimize the index signal.

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